The White House on Wednesday defended the use of the interrogation technique known as waterboarding, saying it is legal -- not torture as critics argue -- and has saved American lives. President Bush could authorize waterboarding for future terrorism suspects if certain criteria are met, a spokesman said.

The U.N.'s watchdog agency on torture will question U.S. officials over their compliance with a global ban on prisoner abuse, focusing on allegations of secret CIA prisons and flights transferring suspects for possible torture in other countries.

The abuse of Iraqi prisoners by U.S. troops has put a spotlight on one of the murky aspects of America's war on terrorism: the aggressive physical and psychological techniques that intelligence agents are using to try to extract information from reluctant or hostile sources.